Method of coating a porous web with ink



March 30, 1965 R. A. M RAE METHOD OF COATING A POROUS WEB WITH INK Filed July 16, 1962 mvsmon ROBERT A. McIZAE flaw. M

ATTORNEY United States Patent 3,175,925 METHOD OF COATING A POROUS WEB WITH INK Robert A. McRae, Old Tappan, N.J., assiguor to Butroughs Corporation, Detroit, iVIiciL, a corporation of Michigan Filed July 16, 1962, Ser. No. 209,912 3 Claims. (Cl. 117--111) This invention relates to coating apparatus, and to multiple roll apparatus for coating a fluid substance on a web.

At the present time, there are many types of multiple roll apparatus available for applying decorative, protective, or useful coating on a substrate such as a web of paper or the like. In general, such apparatus may be used with many different types and qualities of webs and coating materials. However, each coating apparatus has a limit with respect to the thinness of web material which may be coated. Considering, for example, apparatus for preparing carbon paper by coating an ink on a paper web, known apparatus cannot be used in mass production for applying a coating of ink to a highly porous paper, such as twisting tissue. It has been found that, when an ink is coated on an extremely porous paper of this type, the ink passes through the paper and gradually accumulates on the roll which supports the paper. Eventually, such accumulation causes Wrinkles and other non-uniformities to develop in the coated paper.

Accordingly, the objects of the invention are concerned with the provision of improved apparatus for applying coatings to thin and porous web material.

Briefly, the apparatus of the invention includes means for transferring coating material from a source to the web material. This means includes a transfer roll which applies the coating ink directly to the web. Means are also provided for feeding the web material from a supply reel to the coating transfer means. This means includes a feed roll on which the web is carried as it is contacted by, and coated by, the transfer roll. According to the invention, a plurality of thicknesses of the web material is passed through the coating region between the transfer roll and feed roll so that the coating material cannot pass through the web and onto the surface of the feed roll.

The invention is described in greater detail by reference to the single figure of the drawing which is an elevational, schematic view of apparatus embodying the invention.

Coating apparatus embodying the invention may be used for applying a coating of a transfer material, such as an ink, to a paper web, and the following description of the invention is directed toward this use of the apparatus. However, it will be clear to those skilled in the art that the invention may also be used for applying many different types of coating materials to many diiferent types and qualities of webs other than that specifically described. The invention is particularly useful for applying coatings on extremely porous papers, an operation which has not been possible in the past.

Coating apparatus 10 embodying the invention is shown in the drawing and includes a supply reel 14 of paper 16 to be coated, which, for optimum operation and simplicity, is mounted directly beneath the means for applying coating material to the paper. The apparatus 10 also includes a suitable source (not shown) of ink which is transported by any convenient number of rolls (not shown) to a rotatable ink transfer roll 20. The transfer roll, preferably, has a soft, resilient surface, which may be provided by a blanket of synthetic rubber, such as neoprene, having a hardness of approximately 80 to 90 durometers. The transfer roll is provided with a shaft 24 on which it rotates and which is preferably hollow so that a temperature-controlling fluid may be circulated ice through the roll. The shaft 24 may also carry at its ends suitable gears 30, or the like, by which it may be rotated. The transfer roll 20 is suitably supported by means not shown for vertical and horizontal adjustment to regulate the pressure of its contact with the adjacent web-feeding roll 34.

The web-feeding roll 34 is positioned adjacent to, and preferably horizontally axially aligned with, the transfer roll 20. Roll 34, preferably, has a hard surface, for example of stainless steel, and is also provided with a shaft which carries gears 42, or the like, by which the shaft is rotated. The shaft 40 is also preferably hollow so that a temperature-controlling fluid may be circulated through the roll 34. A plurality of chili or idle rolls 46 are mounted adjacent to, and following, the feed roll 34, if such are required. Any suitable number of guide rolls (not shown) may also be provided for lead ing the web, after being coated, to a takeup reel 50 which is suitably coupled to, and driven by, a motor 54. The motor, or other power source, is also suitably coupled to the transfer roll 20 and web-feeding roll 34, which are positively driven thereby. This coupling is represented by dash lines 35.

According to the invention, in order to coat ink on a paper 16 which is very porous, the paper is fed from the supply reel 14, between the ink transfer roll 20 and webfeeding roll 34, over the feed roll and back to and over the supply reel, between the transfer and feed rolls again, and finally over the various chill and guide rolls to the takeup reel 50.

With this arrangement for threading the paper, a double thickness of paper is present in the area where the coating operation occurs, between the rolls 20 and 34. Thus, if any coating material penetrates through the first layer of paper 16' as it is applied thereto, it is absorbed by the second layer 16" of paper underneath and is thus prevented from reaching the roll itself. It is to be noted that the coated surface of paper 16 can be transported without contacing any of the rolls of the apparatus iii.

For optimum performance of the coating operation and to allow minimum penetration of coating material into the paper being coated, the feed roll 34 is operated at a relatively low temperature, for example to F., or the like. The desired temperature may be achieved, for example, by flowing a suitable fluid from a source 70 through hollow shaft 40 on which the roll rotates. The operating temperatures of the other rolls of the apparatus may be adjusted in similar fashion. Means for obtaining temperature control are well known and are not shown in detail.

The present invention has the important advantage that it allows the coating of thinner and more porous, and thus more inexpensive, paper than could be coated in the past. As an example, one type of coating apparatus which could previously provide a coating of desired weight on paper no thinner than kraft paper can now coat the same weight of ink on twisting tissue. In this case, a saving of about ten cents per pound in the paper is realized.

It is clear from the foregoing description of the invention that the principles thereof are broadly applicable to other types and arrangements of coating rolls and the like than that described. In addition, the principles of the invention apply to different types of coating materials and different types of web materials.

What is claimed is:

1. The method of coating a porous web with an ink comprising the steps of mounting a coating roll adjacent to a support roll,

the support roll being adapted to support a web to be coated and the coating roll being adapted to apply ink material to the web,

mounting a supply roll of web material adjacent to said coating roll and supply roll,

applying uncoated web material from said supply roll in a plurality of layers over said support roll,

and then applying ink to the top layer of the plurality of layers of webs supported by said support roll.

2. The method of coating a porous web with an ink comprising the steps of mounting a coating roll adjacent to a support roll,

the support roll being adapted to support a web to be coated and the coating roll being adapted to apply ink material to the web,

mounting a supply roll of web material adjacent to said coating roll and said support roll,

leading said Web from said supply roll over said support roll,

passing said web over the surface of said support roll and then again passing said web over said support roll whereby two layers of uncoated web are present on the surface of said support roll,

and then applying ink to the top layer of the webs supported by said support roll.

3. The method of coating a porous web with an ink comprising the steps of mounting a coating roll adjacent to a support roll, the support roll being adapted to support a Web to be coated and the coating roll being adapted to apply ink material to the web,

mounting a supply roll of Web material adjacent to said coating roll and said support roll,

leading said Web from said supply roll over said support roll,

passing said web over the surface of said supportroll and then again passing said web over said support roll whereby two layers of uncoated web are present on the surface of said support roll,

then applying ink to the top layer of the webs supported by said support roll,

and then winding the top layer of coated web on a takeup reel.

References Cited by the Examiner UNITED STATES PATENTS 1,439,183 12/22 Martin.

2,114,618 4/38 Wallin l1868 2,513,394 7/50 Barrett et al 1l8--262X 2,763,572 9/56 Staehle 117--64 2,770,215 11/56 Knight.

2,969,865 1/ 61 Long.

25 RICHARD D. NEVIUS, Primary Examiner. 

1. THE METHOD OF COATING A POROUS WEB WITH AN INK COMPRISING THE STEPS OF MOUNTING A COATING ROLL ADJACENT TO A SUPPORT ROLL, THE SUPPORT ROLL BENG ADAPTED TO SUPPORT A WEB TO BE COATED AND THE COATING ROLL BEING ADAPTED TO APPLY INK MATERIAL TO THE WEB, MOUNTING A SUPPLY ROLL OF WEB MATERIAL ADJACENT TO SAID COATING ROLL AND SUPPLY ROLL, APPLYING UNCOATED WEB MATERIAL FROM SAID SUPPLY ROLL IN A PLURALITY OF LAYERS OVER SAID SUPPORT ROLL, AND THEN APPLYING INK TO THE TOP LAYER OF THE PLURALITY OF LAYERS OF WEBS SUPPORTED BY SAID SUPPORT ROLL. 